1. Field of the Invention
The present invention relates to a metal manufacturing, and more particularly, to a metal rolling mill.
2. Description of the Related Art
Many earlier inventions that relate to the four-roll metal rolling mill design can be found in the following US Patents:
U.S. Pat. No. 2,019,081, titled Universal Roll Mill, by Heinrich Koppel in 1932 PA1 U.S. Pat. Nos. 2,041,271 and 2,071,712, titled Roll Stand Unit for a Continuous Reducing Mill, by Heinrich Stutting in 1934 PA1 U.S. Pat. No. 2,094,920, titled Rolling Mill, by Heber C. Inslee in 1937 PA1 U.S. Pat. No. 2,495,387, titled Mill, by Richard E. Rummins in 1950
All of the inventions above implemented a metal rolling mechanism that was based on four rolls and therefore shared many common characteristics. Most notable of which was that although their respective novel approaches to a four-roll-based design were theoretically and mechanically sound, however, the entailed press systems became extremely complex and bulky. The large number of bevel and other types of gears that are necessarily used in such systems reduce gearing transmission efficiency and subsequently usability of the inventions. This major disadvantage most likely accounts for the reason of why these inventions never saw practical use in the metallurgical industry.
A more interesting and modern instance of prior inventions that was also based on a four-roll mill design can be found in U.S. Pat. No. 5,144,827, titled Rolling Mill Stand, by Itsushi Iio in 1992. This invention far surpassed its predecessors in the 30's and 50's in terms of design and usability. In this invention, a single shaft is used to drive four coplanar shafts that are at right angle with respect to one another. Three pairs of bevel gears on the shafts transmit torque in between the driven shafts at 90.degree. and cause the helical gears and the rolls on the shafts to rotate synchronously. The four driven shafts were made eccentric so that they could rotate off-center to achieve the effect of adjusting parting in between the rolls. After careful analysis of the patent, it was found that the overall design of structure in this invention was relatively novel but not without its shortcoming. The implementation of a single shaft driving two pairs of shafts via three pairs of bevel gears and four pairs of helical gears to attain synchronous rotations of the shafts and rolls resulted in low transmission efficiency and lower structural integrity of the rolling components. Bearings of other types and higher strengths could not be used to remedy the weakness in the components due to structural limitations, which inevitably rendered the overall rolling system incapable of sustaining higher rolling torque. The lack of public knowledge of this invention in the industry today can most likely be traced to these major disadvantages. This present invention aims to eliminate the shortcomings and disadvantages found in various prior inventions as described above and further improve upon the technical merits associated with the four-roll-based design. It is hoped that through this invention, the theoretically superior four-roll technology can finally be flawlessly implemented.